Broadband VHF/UHF Amplifier Design Using Coaxial Transformers

[bubuta77]

Hi all.
1. In given article:
https://highfrequencyelectronics.com/Archives/May03/HFE0503_Leong.pdf
at figure 2, the inductors suppose to simulate ferrite?
2. Additional question: for what exactly we need ferrite here?
3. Do somebody have some detailed tutorials/books for learning design of PA's for VHF/UHF (below 500MHz)?
Thanks a lot

 

[FvM]

Transmission line transformers are a good tool to design broadband matching in PAs. If you don't need the broadband feature, you'll come along with standard LC impedance matching more easily. You'll find a lot of similar designs at www.polyfet.com

A transmission line transformer simulation must reflect the common mode impedance, usually by additional transmission line elements. In a transmission line transformer with core, the common mode impedance is increased compared to a coreless design, in the shown circuit, the common mode transmission line is omitted because the core inductance dominates the common mode impedance.